Honda 10hp Won't Idle

[Grant Brown]

I have a 1990 or so Honda 10hp Blue/White w yellow prop. For some strange reason it won't idle. Starts fine and runs at higher RPM, but as soon as I let off it dies. It ran good up until last summer and then started acting up every second or third trip out.
I cleaned the carb 4 times ( even had a buddy who works for the city small engine repair shop put it all in the ultrasonic tank), I tried pumping the primer bulb, replaced primer, hose and the fittings w new, checked and cleaned the fuel pump 2x, checked for air leaks at base of carb with ether, replaced the plugs and even convinced another buddy with a good running 8 hp to try his carb and fuel pump on mine just to eliminate them. Nothing helped it - still won't idle.
This has been a great motor but I have almost had enough. I am looking for a replacement, but I would rather spend the money elsewhere right now.
Grant
White Rock, BC

 

[isaksp00]

Re: Honda 10hp Won't Idle

I was going to suggest poking a thin copper wire strand through the low speed (pilot) jet, until you mentioned you swapped carbs. I had somewhat similar symptoms on my 1993-ish 8HP Honda, and that seemed to fix it. Mine was hard to start, and stalled when put in gear (unless I revved it up higher than advisable). You may want to try that, just in case, since (at least on mine) that jet is easy to remove.

Other than that (I'm no mechanic), maybe electrical? But what electrical component would affect only idle? I am very curious what the root cause is, if you get to it.

 

[isaksp00]

Re: Honda 10hp Won't Idle

Here's an update of my issues, that may help you. As I noted, cleaning the carb had seemed to fix my inability to stray running at idle, based on testing in a can of water in my basement.

Well, I launched the boat today and the same symptoms appeared as soon as I fired up the outboard at the dock - stalled when throttled down to idle. After I tried some adjusting, I bit the bullet and removed the low speed jet (it is accessible on the side of the carb on mine). I sprayed some carb cleaner, and gently poked a single strand of copper electical wire down the thin center jet hole. Screwed it back in, and lo and behold the engine ran smoothly, idled, and did not stall when put in gear. Motored around for about 30 mins to test, and so far so good.

These carbs seem to be incredibly sensitive to debris - I installed a new fuel filter, new internal fuel lines and a new hose from tank to bulb, and it still had some kind of problem after having run it all of 15 mins or so, in my basement. I ran the engine without the fuel hookup to drain the carb before I removed it from the basement. I wonder if there's some extra kind of filter that might help?

 

[Grant Brown]

Re: Honda 10hp Won't Idle

I had a friend of a friend (who is supposedly a small Honda outboard expert) suggest a compression test. Says they won't idle with low compression.
I will try the strand of wire through the jet then the compression test.

 

[Schultz]

Re: Honda 10hp Won't Idle

I had a similar problem. After hours of tweaking and adjusting the idle screw and air bleeder screw, cleaning the carb, installing a new fuel filter. I then adjusted/tightened the throttle control cable and then adjusted where the mechanical rod is held by a screw to the linkage (where the wire hooks up to the mechanical piece of the carb that controls the throttle). It idles a little fast but does so without the choke applied. I hope this helps.

 

[The Admiral and Chief]

Re: Honda 10hp Won't Idle

I have a 82 or 83 BF100 and also have found they are sensitive to debris or fuel problems. It came with a boat I bought last fall and I am told it worked perfectly. When I tested it out, it would not idle.

I had it working well after a cleaning this spring only to have it stop idling last week. Took it off the boat and cleaned the carb again (did not see any debris - put a fine wire through the idle jet port). I have it running again and it seems to be running well but I have concerns about the idle jet setting. From other motors I have worked on, the jet seems to be out much more than I would expect.

My question is: Does anyone know what the initial jet settings are for these engines and where did you find them? I can't seem to find them.

Here's an update of my issues, that may help you. As I noted, cleaning the carb had seemed to fix my inability to stray running at idle, based on testing in a can of water in my basement.

Well, I launched the boat today and the same symptoms appeared as soon as I fired up the outboard at the dock - stalled when throttled down to idle. After I tried some adjusting, I bit the bullet and removed the low speed jet (it is accessible on the side of the carb on mine). I sprayed some carb cleaner, and gently poked a single strand of copper electical wire down the thin center jet hole. Screwed it back in, and lo and behold the engine ran smoothly, idled, and did not stall when put in gear. Motored around for about 30 mins to test, and so far so good.

These carbs seem to be incredibly sensitive to debris - I installed a new fuel filter, new internal fuel lines and a new hose from tank to bulb, and it still had some kind of problem after having run it all of 15 mins or so, in my basement. I ran the engine without the fuel hookup to drain the carb before I removed it from the basement. I wonder if there's some extra kind of filter that might help?